In finishing equipment in the graphics industry, sheet feeder devices may drop signatures perpendicularly to a conveying apparatus, such as a chain conveyor, moving below the feeder device. Signatures leaving the feeder grippers may only be moving downwards and are not translated tangentially with respect to the conveying apparatus (i.e., in the horizontal direction). So, just before the signatures contact the conveying apparatus the signatures may have a tangentially velocity of zero. When each signature contacts the conveying apparatus, due to the velocity difference the signature may slide a very small distance, then begin traveling at the same tangential velocity as the surface of the conveying apparatus. Conveying apparatuses may have lugs to positively register and align the signatures. The immediate tangential acceleration of the signatures by the conveying apparatus may cause the lugs or the surface of the conveying apparatus to mark or damage the signatures. As a result, the velocity of the conveying apparatuses may sometimes be limited to minimize the tangential velocity difference between the signatures and the conveying apparatus.
FIG. 1 schematically shows a perspective view of a conventional signature transporting device 110. Signature conveying device 110 includes a feeder device 112 and a collecting apparatus 114. Feeder device 112 includes a pair of transfer drums 116, 118 rotatable in one direction about a first axis 120 and a pair of opposing transfer drums 126, 128 rotatable in the opposite direction about a second axis 130. Drums 116, 118 may have grippers that grip an open edge of a folded signature and drums 126, 128 may have grippers that grip the other open edge of the folded signature. Drums 116, 118, 126, 128 may receive the open edges of each signature first and transport the signature downward while moving the open edges away from one another to open the signature. The signature is then released downwardly by the drums 116, 118, 126, 128 to collecting apparatus 114, which may be a chain or a saddle conveyor.
Axes 120, 130 are aligned horizontally with respect to a direction Y and drums 116, 118, 126, 128 transport signatures vertically downward in a direction Z. Collecting apparatus 114 receives signatures traveling vertically downward in direction Z and transports the signatures horizontally in direction Y. Axes 120, 130 are rotatably fixed in position, such that drums 116, 118, 126, 128 are not translatable in a direction X, direction Y or direction Z. Therefore, drums 116, 118, 126, 128 only convey signatures in direction Z and just before signatures contact collecting apparatus 114, signatures have no velocity in direction Y.